On March 14th, 1990, the Grateful Dead opened a six-city, 16-show tour at the Capital Centre in Landover, Maryland. Singer-guitarist Bob Weir remembers that sprint as "the high point of that era." The following July, keyboard player Brent Mydland suffered a fatal drug overdose. In August 1995, lead guitarist Jerry Garcia died of a heart attack, effectively ending the band.

But in the spring of 1990, Weir contends, "We were hot, feeling our oats and surprising each other on stage. The jams had personality and space. We were in good shape and had nothing better to do than get down on the music."

The proof officially arrives on September 1st in an 18-CD box, Spring 1990, released by Rhino and available for pre-order at dead.net. The set, limited to 9,000 copies and costing $199.98, features six complete concerts, one from each venue on that tour, with deluxe packaging and a 60-page hardcover book. The shows in Spring 1990 will not be sold individually, but Rhino is also issuing a two-CD compilation drawn from the box.

Aside from a few tracks from a date in Albany, New York, the shows are previously unissued, and the set lists cover the Dead's lifetime to that point, from "Morning Dew" on their 1967 debut LP to "Picasso Moon" from 1989's Built to Last. "The improvising is great," says the box's producer, Dead archivist David Lemieux, who saw 10 shows on the tour as "a 19-year-old Deadhead." But what distinguishes Spring 1990 "is how the Dead play smaller songs like 'Big River' with such furious energy – and nailing it."

Weir and drummer Mickey Hart spoke about the new box and that tour for a story in the new issue, on newsstands Friday, August 3rd. Here is more from those conversations.

How would you describe Garcia's health at the time of the shows in this set? He'd been through the coma in 1986, but his playing is strong and focused on this tour.Bob Weir: He was eating well. He was off the Persian. And he was living life to the fullest, at least for him. For instance, he took up scuba diving. He insisted that I join him in Hawaii, so he could show me around down there. He was loving life and having a good time. He was out of the darker bag he'd been in.

There is an energy and love of performing, a spirit of continuing renewal, in these performances, in the way you cover the band's whole life on record in the set lists and in the Traffic and Band covers you added to the rotation.Weir: A lot of those songs were actually broken out the night they were delivered on stage. I remember the Paul McCartney tune, "That Would Be Something" [from 1970's McCartney] – we were in a jam one night, and that just came out. [The Rolling Stones'] "The Last Time" and [Spencer Davis Group's] "Gimme Some Lovin'" came back around the same way.

We were real open, so it wasn't hard to hear suggestions, either in the back of your head or in what someone else was playing, that would take us to a new place. There were a lot of jams that were one of a kind, with their own personality and space. It was a hopping era for us.

How much did your 1987 tour with Bob Dylan expand your covers repertoire? Folk and blues standards were always vital to your shows, but did working with his catalog open you up to that classic era of rock songs?Weir: Touring with Dylan reminded us that within the song there is a poem. And within the poem, there is a character telling the story. And that's where the song lives. There is a kernel of something that is bigger than the notes, bigger than the poetry. And that is the song. Our tour with Dylan reawakened us to that notion. We took the bit and ran with it.

There is a stunning momentun and consistently high quality to the shows from this tour, which is regularly cited by Deadheads as one of your best. Yet by mid-summer, Brent Mydland was dead. What changed?Weir: Probably chemicals. I think it was getting too much for Brent. When I first met Brent, he was a temperate, modest soul. Inside the Dead, the enormity of that endeavor proved to be too much for him. When we got to this peak in the spring of 1990, things were going almost too well. It was straight-up too much too soon for him, even though he had been in the band 10 years. He was living on brinksmanship. It was as if he became a victim of his own success.

The Spring 1990 tour marked your 25th anniversary as a working group. Yet you were playing at a higher rate of excellence and adventure than a lot of bands half your age.Mickey Hart: With In the Dark, we had to start defending the shows. People were breaking in. It was 50,000 people inside, 50,000 outside. There was a lot of pressure on us to keep the peace. But it was hot on all fronts – the band was in a good playing place. Brent was really cranking, and we were bringing a lot of the old stuff out – "Death Don't Have No Mercy," "Attics of My Life." There was no pressure to reinvent. We were just being the Grateful Dead. And Jerry was feeling good.

Your "Drum" spot with Bill Kreutzmann was an established part of the shows but also a place where anything could happen. How much did you and Bill talk about what to play – and what was new to do?Hart: We never did. That was one of the rules of "Drums" and "Space." It was a place we left barren as far as talking about or arranging anything. Sometimes we'd have fun with stuff. If we were in Las Vegas, I'd sample the slot machines and make that part of it. It was a surprise to Bill, and we'd both react on it.

We'd play with the band all night on drums, so we were anxious to get off to a new space, like open-field running in football. It was the place where you could take a deep breath, relax and create something in the moment, as opposed to recreating something and embellishing it, which is what jamming [on a song] is all about. This was making it happen in the moment.

In the first show in this box, at the Capital Centre, you play the hit single "Touch of Grey" right away: second song, first set, as if to say, "Let's get this out of the way."Hart: [Laughs] Yeah. Everybody wanted us to play it, Clive [Davis, Arista Records president] and all. In good old Grateful Dead spirit, we were like, "No, man, we're not gonna be that band that goes out and plays its hit. That's so lame." The most important thing was to be the Grateful Dead.

But this Spring 1990 set is significant in that previous tour boxs, like the complete Europe '72 suitcase, covered older, historical eras. This one shows the Dead in their adult prime – still relevant and charged fairly late in your history.Hart: The Grateful Dead meant a lot to us. It was everything. And to let it go, to peter out after all we'd been through, was unthinkable. We had a burst of energy around that time, because of the hit. A hit brings a whole bunch of energy, negative and positive. The kids breaking down the stadium doors – they almost killed what they loved the most. They almost put us out of business.

But that created an energy that we transferred into the music. We were energized by that hit – and reacting against it. The hard thing is, as [Ken] Kesey said, to stay within your own movie. We were able to do that on this tour.